I'm in the JS ecosystem pretty regularly and "restrictive with no benefit" is the right description. I use JSON5 now when I have to, which greatly reduces the restrictions. I already have a build step so throwing in a JSON5 -> JSON converter is negligible.

As for FracturedJson, it looks great. The basic problem statement of "either minified and unreadable or prettified and verbose" isn't one I had put my finger on before, but now that it's been said I can't unsee it.